Marshall combines mystery with urban fantasy to create an eerie, convoluted tale of shadow beings living between the cracks of our world. While visiting New York City, writer David Miller encounters a stranger who says cryptically, “Remember me.” Meanwhile, John Henderson (protagonist of 2009’s Bad Things) and his girlfriend, Kristina, investigate her friend’s stalker, who they discover belongs to a society of mysterious entities. These people, who call themselves “friends,” might be ghosts or forgotten imaginary friends whose creators have grown to adulthood. They have their own factions and agendas, some of which threaten John, Kristina, David, and those David loves. While allusions to John’s past can be distracting, and some explanations are delayed so long that readers might be tempted to flip ahead for context, Marshall depicts interactions involving John and Kristina with realism and warmth. He excels at endowing the ephemeral “friends” with complex motives and emotions, making them as engaging as his most finely drawn flesh-and-blood characters. (Feb.)